fix(ui): prevent example select from overflowing (#7060)

src/core/components/examples-select.jsx

@@ -109,6 +109,7 @@ export default class ExamplesSelect extends React.PureComponent {
           ) : null
         }
         <select
+          className="examples-select-element"
           onChange={this._onDomSelect}
           value={
             isModifiedValueAvailable && isValueModified